Following the MOPA (Master Oscillator Power Amplifier) technology, a new generation of laser technology, represented by multipass amplification, has greatly promoted the development of high-power laser devices, but there are still many problems. First, in order to extract the energy in the medium, prior designs required expensive pre-amplifier system, as greater front-end energy has been utilized to compensate for the limited gain of the main amplifier system; second, in order to isolate ASE, an off-axis design is required in prior designs, which leads to the vignetting losses; third, in the prior art devices, the variable-aperture single-pulse unidirectional transmission amplification is usually used, with the amplifier having a low stored-energy extraction efficiency; fourth, the whole system is complex and bulky, costly, and high in the maintenance costs.
Therefore, it is necessary to propose a novel laser amplifier configuration, so as to solve the existing problems of the prior art laser amplifier.